This system is completely different from the four other groups of trap-jaw ants, which use a simple combination of latch, spring, and trigger to catch their prey. The latch holds their jaws open so that the ants can use their muscles like a spring. This loads the jaws with tremendous amounts of power that are released when triggered.

Though the jaws look similar among the five types, Myrmoteras has its own mechanism—an example of what's called convergent evolution.

Suarez and study leader Fred Larabee, an entomologist at the Smithsonian's National Museum of Natural History, recorded the ants catching springtails, their primary prey, using video cameras that record at 50,000 frames per second.

Escape From the Jaws of Death

The team noticed that while hunting, the ants keep their jaws open at a 280-degree angle—a strategy that stores elastic energy and allows them to shut their mandibles in a fraction of a second, according to the study, published August 30 in the Journal of Experimental Biology.

Reviewing the footage, the scientists calculated the jaws move at about 50 miles per hour.

The scans revealed two crucial, never-before-seen sets of muscles: A large set that load the jaws with potential energy—generating enough force to create that small indentation on the back of the head—and a smaller set that releases the jaws when it senses the trigger.

“We know pretty little about these ants—that’s why this paper is kind of a big deal," says Sorger, who studies Odontomachus ants but wasn't involved in the new study.

"They used really cutting-edge techniques to study a beautiful example of convergent evolution."